This is my take on what Celestia would write in a 4th wall letter to us - The brony fandom - about our portrayal of her.

An undead Emperor in need of a new body. A Spartan lost in space. A ragtag team on a suicide mission. What do they all have in common? They all wind up on the magical world of Equestria, where war has been forgotten. That, however, is soon about to change.
When each of them is about to be retrieved, ancient evils arise to unleash hell upon the unsuspecting world. When the forces of three galaxies clash around them, can our favorite ponies hold out against the onslaught?
This is a crossover involving Warhammer 40k, Halo, Mass Effect and MLP, and is also my first fanfic. Comments and reviews are welcome.
Rated T for language, violence, and general adult situations.
Now on Tv Tropes!

This is a Fallout Equestria (primarily) and Terminator crossover.

As the war between Equestria and the zebras pressed on, many members of the Ministries conceived of desperate strategies to end it through magical and technological creations of questionable nature. One of these was Project Infiltrator, a top secret project of the Ministry of Awesome. It's goal: to create a super spy that was the perfect blend of pony and machine. But just as its first subject was ready, the megaspells dropped, destroying Equestria and creating the Wasteland.

190 years later, Crystal Eclair awakens in a world of ruin and violence, completely clueless as to what happened to Equestria and herself. Her confusion grows into horror as she discovers that she is no longer a pony, but now a cybernetic zebra. With no other choice left, she sets out to find answers to her predicament. How will she handle the truth if she finds it? Will she find friends who can help her in a world that trusts no one? And what if those who have done this to her are still out there, eager for her to serve a new sinister purpose?

PS. This is not a Prequel to Broken Steel despite what a couple of websites that link back to this story say.

(Chapters 1 to 12 Edited by Alycorn~(CF), New Editor Double R Forrest. New description credit to Double R Forrest )